Furniture-caster.



No. 643,7l9.

- Patented Feb. 20, |900. W. LIVINGSTONE. FURNITURE CASTER. (Applicationmed Ju'ly 2o, 1899.)

(No Modal.)

- LNITED STATES WILLIAM LIVINGSTONE, OF NEW YORK, N. Y., ASSIGNOR TOROBERT lVIURRAY, TRUSTEE, OF SAME PLACE.

FU RNITU RE-CASTER.

SPECIFICATION forming part of Letters Patent No. 643,719, dated February20, 1900.

' Application led July 20, 1899. Serial No. 724,507. (No model.)

To LLZZ whom t may concern:

Beit known that I, WILLIAM LIVINesToNE, a citizen of the United States,residing at New York, (Flushing,) in the county of Queens and State ofNew York, have invented certain new and useful Improvements inFurniture-Casters; and I do hereby declare the following to be a full,clear, and exact description of theinvention, such as will enable othersskilled in the art to which it appertains to make and use the same.

My invention relates to improvements in that class of furniture-casterswhose general principle of construction rests upon the displacement ofthe axis of the wheel from the perpendicular axis of the swivel-pin andcommonly known as horn-casters, as contra-A distinguished fromball-casters, in which the' ball itself is made to rotate horizontallyrand vertically in a direct line with the frame or tube containing it. Asto the merits of the two classes it is certain that the rst has theadvantages of a more sensitive action of rotation in both directions andof greater simplicity and cheapness of construction. method ofconstruction, however, has the disadvantage that the load or weightresting upon the caster will not exert its greatest pressure on the lineof the axis of the swivelpin as the natural axis of the caster, but uponthe axis of the wheel outside thereof, and produce a canting strain,which will either force the swivel-pin out of its perpendicular andproduce extreme friction at the upper end of the pin farthest from thewheel and at the lower end nearest to the wheel, as in the case ofpin-casters, or this canting strain will press the upper surfaceof thehorn or any auxiliary ball or roller bearing used for the purposedirectly above the center of the wheel tightly against the upper plateor swivel-plate and loosen the contact between the same in thediametrically-opposite direction, as in the case of so-calledplate-casters. This canting strain actin g during the rotation of thehorn around the swivel-pin at every point of the circle it describes hasthe mostdestructive eect upon the screws which hold the swivel-plate tothe furniture-leg or other object, and it is only a question of timewhen they will get loose and the caster fall off alto- This gether.Another grave imperfection in the present method of construction is theshearing strain upon the wheel-pin, upon which the whole weight abovethe caster directly rests and makes the upper side of the hole in thehorn and the lower side of the'hole in the wheel form two direct-actingcutting edges against the upper and lower side of the pin, and even ifthe pin is strong enough to resist that shearing strain it is certainthat the hole in the wheel in course of time will become elongated, itsmotion jerky, Yand finally it will not move at all. My inventioncontemplates the construction of a horn-caster-either pincaster orplate-caster-which shall be free from these objections without eitherchanging its present general appearance or making the same morecomplicated in construction or more expensive in price.

The geometrical principle underlying the present method of constructionis a right-angled triangle one side of which is the horizontal radiusfrom the center of the swivelpin to the intersection of it with theperpendicular line to the center of the wheel-pin. Another is theperpendicular line from said point of intersection to the center of thewheelpin, and the third is the hypotenuse from the center of thewheel-pi n to the center of swivelpin. The weight resting uniformly uponthe horizontal side of the triangle will naturally have a tendency toforce and twist and swing the hypotenuse outward and the perpendicularupward and create a point of forced contact between the horn and theswivel-plate. The rotary motion of the horn around the swivel-pin willproduce a circular line of forced contact concentric with theswivel-pin.

The first object of my invention-namely, an easy, sensitive, andreliable rotary motion, of the horn around the swivel-pin without anycanting strain in the direction of the center of the wheel-I attain bythe simple method of making the hole in the upper part or crown of thehorn through which the swivel-pin is to pass not in the center of thehorn, as is done now, but as near as possible to that point of itscircumference farthest back from the wheelpin, giving to the crown ofthe horn and to the groove forming the ball-race'an eccentric form andappearance which will make the IOO horizontal side of the triangle fromthe center of swivel-pin to the most forward point of contact twice aslong as the horizontal distance from the center of the swivel-pin to thecenter of the wheel-pin, while the two other sides, from the mostforward point of contact to the center of the wheel-pin and from thecenter of the wheel-pin to the center of the swivel-pin, are the equalsides of an isosceles triangle. All the weight pressing, therefore, uponthe horizontal side of this triangle will be carried equally upon bothsides of the center of the wheel without a tendency to canting ortwisting.

The second object of my invention\'iz., of reducing and removing thecutting and shearing strain from the wheel-pin and maintaining an easyand uniform rotary motion of the wheel-I attain by putting the weightdirectly upon the Shanks of the horn instead of upon the wheel-pin bymeans that will be fully described in connection with the drawings.

The object of my invention and methods of construction as illustrated inthe accompanying drawings have been preferably adapted to plate-casters;but it is to be borne in mind that they may be and are intended t0 beapplied with equal advantage to pin-casters.

In the drawings, Figure 1 is a side elevation of acaster. Fig. 2 is alateral section of horn, swivel-plate, and swivel-pin, showing one halfof wheel with strengthening-ring and prongs and one half without it.Fig. 3 is a front elevation. Fig. t is a section of casterthroughline:0.1,sliowingconicalprojectionsof horn with surrounding tubeand wheel-pin riveted against the outside of the shanks, also a sectionof half-wheel shells clenched together by prongs of an innerstrengtheningring. Fig. 5 is/a half-plan of swivel-plate and half-planof horn, showing eccentricity of ball-bearing. Fig. 6 is an end view,and Fig. 7 a top view, of the strengthening-ring; and Fig. S, a blankfrom which the strengtheningring with prongs is formed. Fig. 9 is anelevation, and Fig. 10 a lateral section, of swivelplate horn andswivel-pin, witha view of the ball-bearing wheel; and Fig. 11, a sectionthrough line f l/ y, showingconstruction of horn with cones on innerside of shanks and integral therewith, also construction of half-wheelshells as adapted to ball-bearings, Figs. 9, 10, and 11 being amodification of wheel and wheel-bearing as shown in Figs. 1 to 5,incluslve. Fig. 12 is a lateral section, Fig. 13

a side view, and Fig. 14 a half-plan, of swivel plate and half-plan ofhorn, Figs. 12, 13, and 14 being a modification of swivel ball-bearingas shown in Figs. 1 to 5, inclusive, by substituting two rollersrevolving on or with a pin for the balls moving in an eccentric groove.Fig. 15 is a side elevation, Fig. 16 a lateral section, and Fig. 17 asection, through line .c z, showing pin and roller above the wheel,being a modification of the construction shown in Figs. 4 and 10 fortransferring the strain to the shank of the horn above the center of thewheel-pin. Fig. 1S is a plan, and Fig. 19 a section, of ahorn, beingamodification of swivel-ball or roller-bearing, as shown in Figs. 1 to 5,inclusive, and 11 to 13, inelusive, by substituting semicircularorconoidal projections for the balls or rollers as bearings for the horn.

Referring to the drawings, A designates the swivel-plate of the caster,b the swivelpin, B the horn, and D the caster-wheel, in all the figures.The general form of these parts of the caster is the same as in thecasters now in use.

The parts of the horn are the top or crown d and the sides or shanks ce.

The swivel-pin h in my caster passes through the center of theswivel-plate A, the same as in casters now in use; but it is theposition of the swivel-pin Z) in the horn which constitutes the novelfeature of my invention.

On the caster illustrated by Figs. 1 to 5, inclusive, the crown of thehorn contains a circular groove g, intended t0 form a ball-race thecenter of which is and shall be substantially indentical with the centerof the horn. Assuming that this groove consists of an inner and outerand a central circle (the latter of which is the line of contact withthe balls) and that the horizontal distance from the center ofswivel-pin b to centerof wheel-piufbe designated as the reach of thehorn, then the central diameter of t-he groove g will be equal to twicethe reach plus one-fourth of the diameter of the swivel-pin, plusone-fourth of the diameter of the ball. The radius of this circle, lessone-half the diameter of the ball and one-half the diameter of theswivel-pin, will be the exact distance of the center of the swivel-pinhole in the crown of the horn from the center of the groove ,r/ on aline running through the center of the groove to the rear end of thehorn B and parallel to the sides or shanks e of the horn. Th us we havethe distance from the center of the swivel-pin l) to the center of therearball h equal to one-half of the diameter of the swivel-pin plusone-half the diaineter of the ball, with just clearance enough for theball 7L to get past the swivel-pin Z1, while the distance from thecenter of the swivel-pin l) to the most forward ball h will be equal tothe whole diameter of the central circle of the groove g, less thedistance from center of swivel-pin to the center of rear ball h. Theeccentricity of the groove g being now established and the center of thewheel being located midway between the most forward bail h and theswivel-pin b, it follows naturally that the weight upon the caster lnustpress uniformly and perpendicularly upon the center of the wheel,the\canting strain will be obviated, and there will be no liabilityeither of straining the swivel-pin or pressing the top of horn or itsball-bearing against the face of the swivel-plate.

\Vhatever the incidental functions of the balls which fill the groove gmay be, it appears IOO IIO

to be certain that only two of them-namely, the nearest to and thefarthest from the swivel-pin and diametrically opposite eachother-control the effective result upon the wheel, and if by any meansthose balls could be confined to their normal position all the otherscould be dispensed with.

On the caster shown in Figs. 12 to 14, inclusive,rollerbearings aresubstituted for the ball-bearings and but two points of contact are madeuse of, both in diametrically-opposite positions corresponding to thenearest and farthermost ball h and h', above described. The edges of thetop of the horn in this modification are turned downward, with holesthrough said downward projection in which a pin or shaft s is made torevolve at right angles to the axis of the wheel. The two rollers h2 andh3, riveted onto this shaft, will revolve with it and supply the pointsof contact with the swivel-plate and produce a similar eiect to theball-bearing, as illustrated in Figs. 1 to 5, inclusive. l

I am aware that casters have been made. with double wheels, betweenwhich a roller has been made to revolve; but inasmuch as such roller wasintended more as an antifriction-roller and its location was nearlyperpendicular over the center of the wheels its use was far removed fromthe objective point of my invention. Another modication of this part ofmy invention is shown in Figs. 18 and 19. In this method the top of thehorn is made to have two half-round or conoidal projections h4 and h5 inlieu of the balls or rollers,providin g fixed points of contact betweenthe crown of the horn and the swivel-plate and producing substantiallythe same result in the most simple and inexpensive manner.

Regarding my improvement for removing and reducing the cutting andshearing strain upon the wheel-pin, I again refer to Fig. 4 of theaccompanying drawings. The sides or shanks e e of the hornB areprovided, as in casters now in use, with holes at their ends, in whichthe wheel-pin is riveted; but my method of making those holes consistsin forcing the same through a very small hole and -utilizing thematerial so displaced to form conical or cylindrical projections or hubsZ l on the inner sides of and integral with the shanks e e. The tube t',around which the wheel is to revolve, is counterbored at its ends eitherto tit tightly or loosely upon the said inner projections of the Shanks.The pin f, which in ordinary casters would be the wheelpin, passesthrough the holes in the shanks and their surrounding projections, aswell as through the tube t', and is riveted against the outside of theshanks. If the tube be tted tight against the projections ZZ, theriveting of the pin will produce a solid fixed bearing for the wheel torevolve upon, being much stronger, because the tube fi, surrounding thepin, forms to all intents and purposes a solid connection between theshanks and projections andthe tube and the pin. On the other hand, ifthe tube t' be tted so as to turn upon the projections Z l the rivetingof the pin without tightening the tube against the inner sides of theshanks will give to the wheel a rolling mot-ion upon the rolling tube.In

either case the weight above the caster pressing primarily upon theShanks and their projections will absorb all or most of the strainbefore the effect thereof could be felt by the wheel or tube z', andleast of all by the pin f.

The Wh eel D itself consists of two half shells or cups la 76,' exactlyalike, and an inner strengthening-ring 0, Figs. 6 and 7. On the sides ofthese cups, next to the inner rims thereof, are a number (preferablyfour) of rectangular perforatious p p p p. The ring ois made from astrip of metal, Fig. 8, of the proper width to lit accurately betweenthe two cups when put together and has prongs r r r r on its two edgescorresponding to the perforatious in the cups, so that when the latterare put together the ring will be forced in one` cup until the prongspass through the perforations,when the other cup will be forced upon thering until the prongs pass through the perforatious and the edges of thetwo cups come close together, when the prongs projecting through theperforatious of both cups are clenched against the outer sides thereof.

Figs. 10 and 1l show a modication of the above method for reducing andremoving the strain upon the wheel-pin, which will produce averysuperior caster. The conical proj ections Z Zon the inner sides ofthe shanks e e are made to an angle of forty-five degrees, more or less,to the face of the Shanks, so as to form proper cones for ball-bearings,while the cups which shall form the wheel are so shaped as to provideproper recesses on their sides to form a ball-race and to secure theballs t in it by suitable ball-retainers. Inas much as by this methodthe weight upon the caster will act directly upon the cones Z Zand ballst, there is no necessity for the tube z', and the pin f being rivetedagainst the indenta-A tions in the Shanks will secure the properdistance between the cones, balls, and ball-races. The innerstrengthening-rin g may or may not be used, as both cups being pressedand held together by the balls and cones in fixed lateral position theycannot separate. Another modification for the same purpose is shown inFigs. 15, 16, and 17. The pin q passes through the upper part of theshanks e in a line parallel to the axis of the wheel and carries aroller q', the under face of which will just touch the upper face of thewheel, whereby the strain will be borne by the shanks through theintermediate pin q and the roller q.

I claim- 1. In a furniture-caster a horn having its top hung on aswivel-pin at a point removed from the true center of the top, andbearingpoints in the same horizontal plane between the horn and theswivel-plate equally distant IOO IIO

from the true center of the top of the horn but unequally distant fromthe swivel-pin the most forward of said bearing-points and theswivel-pin being equidistant from a perpendicular line drawn through theaxis of the caster-wheel substantially as specified.

2. In a furniture-caster the combination with the caster-Wheel and itspin, of a casterhorn or Wheel-hanger having perforated conicalprojections on the inner sides of and integral with the Shanks, throughwhich the caster-Wheel pin is passed and its end riveted therein on theoutside, substantially as specified.

3. In a furniture-caster the combination with the caster-Wheel, of acaster-horn or Wheel-hanger, having perforated conical projections onthe inner sides of and integral with the Shanks thereof, a tube havingcounterbored ends to fit over the said conical projections, and a pinpassing through the perforated conical-projections of the Shanks and thetube and riveted on the outside of the Shanks, substantially asdescribed.

4. In a furniture-castel', the combination of aswivel-plate, aswivel-pin, acaster-Wheel, a caster-wheel horn hung on the swivel-pin ata point removed from the true center thereof, bearing-points between thetop of the horn and the swivel-plate, one of the said bearingpoints andthe swivel-pin being on opposite sides of a perpendicular line drawnthrough the axis of the caster-wheel pin, and a bearing mounted on ashaft Within the horn, the axes of the said bearing-wheel and thecasterwheel being in the same vertical plane, substantially as specied.

In testimony that I claim the invention above set forth Ido aiixmysignature in pres ence of two witnesses.

WILLIAM LIVINGSTONE.

IVt-nesses:

FREDK. HAYNEs, WILToN C. DoNN.

